Can you turn off 4G if not available nearby?

Friend on the "other" network has the EVO and he can turn on and off 4G from the settings menu, says it saves power since it not going to find it where we are with the current state of 4G. I don't see this in our settings menu. Anyone else seen it?

There is not one on it right now, but BMX said that it should come with an update. If not, the developer community should be able to coming up with a toggle switch app/widget. I'm in a 3G only area right now, and my TB has not been searching for a 4G connection that I've seen.